Moons

With four large moons and many smallersm moons, Jupiter forms a kind of miniature solar system. Jupiter has 53 confirmed moons and 26 provisional moons awaiting confirmation of discovery. Moons are named after they are confirmed.

Jupiter's four largest moons—Io, Europa, Ganymede and Callisto—were first observed by the astronomer Galileo Galilei in 1610 using an early version of the telescope. These four moons are known today as the Galilean satellites, and they're some of the most fascinating destinations in our solar system. Io is the most volcanically active body in the solar system. Ganymede is the largest moon in the solar system (even bigger than the planet Mercury). Callisto’s very few small craters indicate a small degree of current surface activity. A liquid-water ocean with the ingredients for life may lie beneath the frozen crust of Europa, making it a tempting place to explore.